1. Technical Field
This invention relates to methods of and apparatus for delivering loaded projectiles for civilian purposes.
The civilian purposes which may be embraced by this invention include, but are not limited to:
seismic exploration utilising explosive signal generators in the form of projectiles launched from a site remote from the location to be explored;
target specific fire fighting utilising projectiles containing fire retardant;
launching projectiles containing matter or objects to be delivered rapidly to a site remote from the launch site, such as difficult to access sites for subsequent retrieval from a containment part of the projectile, and
launching projectiles containing matter to be dispersed from the a projectile in flight above a target zone, such as dispersal of fire retardants or insecticides or other treatment.
This invention has particular application to launching projectiles from a barrel having a plurality of projectiles axially disposed within the barrel and which projectiles are associated with discrete selectively ignitable propellant charges for propelling the projectiles sequentially through the muzzle of the barrel. Sealing engagement is provided between projectiles and barrel so as to prevent rearward travel of an ignited propellant charge to the trailing propellant charge. Such barrel assemblies will be referred to hereinafter as of the type described. Such barrel assemblies are illustrated in earlier International Patent Applications by the present inventor.
2. Discussion of the Background Art
Seismic exploration of the earth's strata is extensively used in oil prospecting, as well as for site investigation in building large scale structures and other civil engineering projects such as for determination of depth to bedrock, delineation of sand and gravel deposits and detection of water-bearing fracture zones and the like in land and marine operations.
The principles of seismic methods of geophysical exploration or mapping are well known. Initially explosive charges were placed to initiate shock waves in the earth's crust. In order to provide appropriate signals a plurality of spaced apart subterranean charges were utilised. While this method is effective the cost of drilling and placement of the charges, mostly in remote areas, is extremely high. On-surface charges have also been trailed, however this did not result in the formation of an effective signal.
In more recent times most seismic exploration has been carried out using a VIBROSEIS type method in which vehicle mounted mechanical vibration apparatus is utilised to instigate the necessary subterranean shock waves. The mechanical vibrating source introduces a definite band of frequencies into the earth. Because of the physical constraints placed on a large vibrating body it is understood that the disturbance produced is in the form of an oscillatory pulse of finite duration in which the frequency changes, substantially linearly with time.
Such systems may have means to vary the frequency of vibration and amplitude of the pulse but such variations are also limited by the mechanical constraints of the particular equipment utilised. The duration of a typical seismic pulse will generally not exceed a few seconds with frequencies within a frequency range between 15 Hz and 90 Hz and with increasing amplitude of the pulse during the event.
Use of these methods is limited to vehicle accessible areas. However seismic signals are provided which enable a more detailed interpretation of the earth's strata to be achieved than is achieved using explosive detonation to generate the seismic signal. However this method is difficult to employ in remote areas and its cost of utilisation in such remote areas is high. There are also significant constraints on the signal type which may be generated, especially utilising mechanical vibration apparatus which of necessity must be by extremely large machines.
In marine operations, the most widely used method of generating seismic signals is to use an air-gun which discharges highly compressed air into the water.
Target specific fire fighting, such as remote fighting a fire in an office of a high rise building has typically been performed by directing a water stream or fire retardant from an elevated platform supported by an extendable ladder. This has limitations imposed by the time required to target the fire and the ability to closely position a nozzle to direct and supply the water or retardant to the site of the fire. Many high rise buildings are simply too high to be reached by ladders.
Fires which extend over a large expanse, either in two dimensions such as a grass fire or three dimensions such as in a bush or forest fire, present particular problems in regard to delivering fire retardant or dousing materials quickly and precisely over threatened areas, whilst minimising risks for fire fighters. Conventional fire fighting techniques typically involve controlling progress of an expansive fire at a perimeter, which may involve back burning. Back burning operations also involve inherent risk, especially in the case of a change in the direction of prevailing winds.
Limitations in delivery of other matter to remote sites are generally well understood.